A significant gender effect was observed in the cohort, but the mechanism behind it remains unclear.

Maternal symptoms of depression during the second trimester of pregnancy, as well as postpartum depression, are associated with alterations in the child's brain structure that may predispose them to later depression and anxiety, according to a multicenter study conducted in Canada and reported in Biological Psychiatry.1

The study examined physical and psychological health records of 52 women recruited during pregnancy from an ongoing health study in Alberta, Canada, and followed the children born to these women for up to 5 years. Depression in the mothers was monitored both pre-and postpartum using the Edinburgh Postnatal Depression Scale (EPDS) once during every trimester and at 2-3 months after giving birth. Magnetic resonance imaging (MRI) of the children's brains (32 boys and 20 girls) was performed at between 2.6 and 5.1 years of age.

During early childhood the cortical gray matter normally thins and white matter becomes less diffuse as the brain matures.2-5 Children monitored in the current study showed these signs of maturation earlier in 2 areas of the brain that correlated closely with depression in the mother. Specifically, reductions in cortical thickness of the gray matter in the right inferior frontal and the middle temporal regions in the children's brains were associated with higher depressive scores in their mothers during the second trimester of pregnancy and again in the postpartum period. White matter changes observed on MRI in the inferior front area corresponded only to depression before birth but not after.

A significant gender effect was observed in the cohort, whereby higher EPDS scores in the mother recorded during the second trimester had greater correlation to changes in cortical thickness in girls than in boys (r= -.80/P < .001 and r= -.55/P= .006, respectively). In the postpartum period the impact of depression in the mother was reversed, as changes the axial, radial, and mean diffusity of the white matter were more significant in boys (r = -.46/p = .015, r = -.57/P = .002, r = -.56/P = .003) than in girls (r = -.09, r = -.07, and r = -.04, all with insignificant P values > .5).

Clinical Implications

None of the mechanisms behind the changes in gray or white matter, including the gender effect noted, are yet clear. The authors pointed out that changes in brain structure in the children were only observed in association with maternal depression in the second trimester of pregnancy and postpartum, suggesting that these are particularly vulnerable times in brain development. White matter changes seemed to be specifically associated with maternal depression after birth.

Reduced cortical thickness of the right frontal lobe has been linked to a higher risk of depression and anxiety in adolescents.6-9 The implication of the current study is that exposure to maternal depression during pregnancy and the postnatal period may cause premature changes in gray and white matter of the child that may lead to depression later on. This finding supports monitoring and appropriate treatment of depression throughout pregnancy and the postnatal period to preserve the mental health of the child.

White matter brain architecture of crossing fibers in frontotemporal connections was shown to be more expressed in participants with better cognitive performance and less expressed in participants with more severe ...